Phosphorylation of cysteine string protein on Serine 10 triggers 14-3-3 protein binding.
Cysteine string protein (CSP) is a neuronal chaperone that maintains normal neurotransmitter exocytosis and is essential for preventing presynaptic neurodegeneration. CSP is phosphorylated in vivo on a single residue, Ser10, and this phosphorylation regulates its cellular functions, although the molecular mechanisms involved are unclear. To identify novel phosphorylation-specific binding partners for CSP, we used a pull-down approach using synthetic peptides and recombinant proteins. A single protein band was observed to bind specifically to a Ser10-phosphorylated CSP peptide (residues 4-14) compared to a non-phosphorylated peptide. This band was identified as 14-3-3 protein of various isoforms using mass spectrometry and Western blotting. PKA phosphorylation of full-length CSP protein stimulated 14-3-3 binding, and this was abolished in a Ser10-Ala mutant CSP, confirming the binding site as phospho-Ser10. As both CSP and 14-3-3 proteins are implicated in neurotransmitter exocytosis and neurodegeneration, this novel phosphorylation-dependent interaction may help maintain the functional integrity of the synapse.
Prescott
Gerald R
GR
The Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Crown Street, Liverpool L69 3BX, UK.
Jenkins
Rosalind E
RE
Walsh
Ciara M
CM
Morgan
Alan
A
D048948:14-3-3 Proteins / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D005089:Exocytosis; D050956:HSP40 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism; D010455:Peptides / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D051381:Rats; D012694:Serine / Q000378:metabolism*
D048948:14-3-3 Proteins; D050956:HSP40 Heat-Shock Proteins; D008565:Membrane Proteins; D010455:Peptides; C088460:cysteine string protein; D012694:Serine